1. Field of the Invention
The present invention relates to a display system, a data driver, and a display drive method.
2. Description of the Related Art
As for a typical display system, there is a liquid crystal (LC) display system. An LC display system includes an LC panel (display panel; more broadly, an electro-optic device), a scan driver that scans scan lines (scan electrodes) of the LC panel, and a data driver that drives data lines (data electrodes) of the LC panel. The LC drive methods available for the LC panel include the passive matrix drive method and the active matrix drive method. The passive matrix drive method is used to drive a passive matrix type LC panel, of which an STN (super twisted neumatic) mode LC panel is a typical example, while the active matrix drive method is used to drive an active matrix type LC panel, in which a TFT (thin film transistor) or TFD (thin film diode) is provided for each pixel or dot.
In a passive matrix type LC panel, voltage is applied to the data lines via sequential selection of the scan lines. A selecting voltage is applied to the scan lines that are selected, and a non-selecting voltage is applied to the scan lines that are not selected. Accordingly, with the passive matrix method, voltage is applied to the selected pixels and to the non-selected pixels.
In an active matrix type LC panel also, voltage is applied to the data lines via sequential selection of the scan lines. But scan lines with non-selected pixels are not selected, so that voltage is not necessarily applied to non-selected pixels.
During drive periods, a display stopping signal such as an initializing signal (reset signal) may be input. At this time, even scanning in the vertical scan direction is stopped midway, voltage is applied constantly to both the selected and the non-selected pixels in the passive matrix method. Therefore, the voltage applied to all of the pixels can be rendered close to zero by applying the non-selecting voltage to all of the scan lines and to all of the data lines.
In contrast, in the active matrix method, the data line voltage can be applied to the selected pixels but cannot be applied to the non-selected pixels. Therefore, when scanning in the vertical scan direction is stopped midway, the electric charges held in the pixels are gradually discharged and the displayed image of the LC panel blurs, resulting in degradation of the display quality.
The present invention has been made in consideration of the above-described technical problem, and a purpose is to provide a display system, a data driver and a display drive method that avoid degradation of display quality due to input of display stopping signals during drive periods in the active matrix type electro-optic device.